spdep (version 0.5-74)

lee.test: Lee's L test for spatial autocorrelation

Description

Lee's L test for spatial autocorrelation using a spatial weights matrix in weights list form. The assumptions underlying the test are sensitive to the form of the graph of neighbour relationships and other factors, and results may be checked against those of lee.mc permutations.

Usage

lee.test(x, y, listw, zero.policy=NULL,
 alternative="greater", na.action=na.fail, spChk=NULL)

Arguments

x

a numeric vector the same length as the neighbours list in listw

y

a numeric vector the same length as the neighbours list in listw

listw

a listw object created for example by nb2listw

zero.policy

default NULL, use global option value; if TRUE assign zero to the lagged value of zones without neighbours, if FALSE assign NA

alternative

a character string specifying the alternative hypothesis, must be one of greater (default), less or two.sided.

na.action

a function (default na.fail), can also be na.omit or na.exclude - in these cases the weights list will be subsetted to remove NAs in the data. It may be necessary to set zero.policy to TRUE because this subsetting ma

spChk

should the data vector names be checked against the spatial objects for identity integrity, TRUE, or FALSE, default NULL to use get.spChkOption()

Value

• A list with class htest containing the following components:
• statistic
  the value of the standard deviate of Lee's L.
• p.value
  the p-value of the test.
• estimate
  the value of the observed Lee's L, its expectation and variance under the method assumption.
• alternative
  a character string describing the alternative hypothesis.
• method
  a character string giving the assumption used for calculating the standard deviate.
• data.name
  a character string giving the name(s) of the data.

encoding

latin1

References

Lee (2004). A generalized significance testing method for global measures of spatial association: an extension of the Mantel test. Environment and Planning A 2004, volume 36, pages 1687 - 1703

See Also

lee, lee.mc, listw2U

Examples

data(oldcol)
col.W <- nb2listw(COL.nb, style="W")
crime <- COL.OLD$CRIME

lee.test(crime, crime, col.W, zero.policy=TRUE)

#Test with missing values
x<-crime
y<-crime
x[1:5]<-NA
y[3:7]<-NA

lee.test(x, y, col.W, zero.policy=TRUE, na.action=na.omit)
#  lee.test(x, y, col.W, zero.policy=TRUE)#Stops with an error



data(boston)
lw<-nb2listw(boston.soi)

x<-boston.c$CMEDV
y<-boston.c$CRIM

lee.test(x, y, lw, zero.policy=TRUE, alternative="less")

#Test with missing values
x[1:5]<-NA
y[3:7]<-NA

lee.test(x, y, lw, zero.policy=TRUE, alternative="less", na.action=na.omit)